Heat-producing compositions are desirable because they feel warm and pleasant sensation on the skin. The warm feeling is typically more appealing than compositions that feel cold when applied to the body and facial skin. This is particularly, the case when using massage products on the body. The relaxation and enjoyment of a massage is rudely interrupted by the anticipation and shock of a cold product being applied to the body, having a normal body temperature. In addition, hair products and hand cleansers can be used with cold water while feeling warmer than the temperature of the water. These products can be warmed in a heated water bath, however, the application of heat to the product may cause degradation of the product by, for example, the occurrence of phase separation, or the breakdown of the active ingredients contained in the product. In addition, the process of heating the product takes time and requires the use of extra equipment such as the water bath.
Another method for creating a warm sensation on the skin is the use of a heat generating agent. Examples of some known heat generating agents in the art, include, but are not limited to, zeolite, iron powders, silica gel, and activated alumina. Another known method of generating heat is to intrinsically establish, within the product, the conditions for an exothermic reaction based on the conversion of hydrogen peroxide to water and oxygen by a catalase. As disclosed in EP 1,050,313, the hot system based on the use of catalase is a type of disinfectant and cleanser used for contact lenses. Catalase is widely distributed in nature and is found in various quantities in virtually all humans and animal tissues. Its use in medicine, however, has been limited due to stability problems. Catalase is known to degrade when subjected to heat as well as being sensitive to low temperatures. Further, catalase is extremely sensitive to light. These problems threaten the stability of catalase regardless of whether it is in solution or stored as a solid. Skin care compositions are also known and are described in WO 01/19331. However, the catalase is not used in a system for creating heat but rather to treat and cleanse skin that has been exposed to solar radiation.
Catalase can be derived from both animal and non-mammalian sources. Bovine catalase is not as active, however, as some other sources such as for example catalase obtained from molds. In particular, U.S. Pat. Nos. 2,635,069 and 5,360,732 disclose catalase obtained from Aspergillus niger. The catalase is prepared by conventional methods of fermenting microorganisms, breaking cell bodies, and purifying the crude extract. It is also known to combine a stabilized gel of the enzyme catalase with hydrogen peroxide to produce oxygen and water on the skin for oxygenation. For example, according to product information published by Agera®, a product by the name of Catalyse Enzyme Gel is to be combined with another product by the name of Aerobic Infusion to provide a boost of oxygen and to soften the skin. In addition, although it is known to encapsulate actives, it is not known in the prior art to use a non-mammalian derived catalase that is encapsulated nor has the prior art recognized the ability to sustain heat achieved as a result of encapsulating the catalase.
It is likewise not known to combine the encapsulated catalase with free catalase and other known heat generating agents in a heat generating system to manipulate and control the rate of heat generated. Typically, regardless of the heat generating agent employed, heat is released such that the intensity of heat is constant during the exothermic reaction. The change in temperature over time on the skin is relatively small, and it is harder for the skin to sense the heat over time because there is little heat. Further, to reproduce the heat, conditions for another subsequent exothermic reaction have to be prepared. Thus, re-application of the entire product is necessary to sustain the warm feeling on the skin. However, the sensitivity of the skin to the heat is diminished and the sensation of heat is less effective. Therefore, there is a need for a product that works with the sensitivity of the skin to heat to provide a sensation of heat in a smooth continuous rate on the skin. The present invention introduces the concept of a sustained heat release such that a temperature-time curve is produced and heat is more easily sensed on the surface of the skin and is substantially non-irritating.